you can't necessarily conclude that Samsung's N3 will be worse because their N8 was worse. Bleeding edge manufacturing requires gambles every couple of nodes with what technology you decide to invest your R&D into. TSMC's mix of lucky and good with EUV patterning won them an advantage over samsung who kept rolling with DUV for 8nm. Intel similarly gambled and fumbled around the same time.

Lots of people were asking why TSMC wasn't charging a higher premium for their 7nm when it was the best process in the world, my theory is that they understand the above and need to maintain relationships for the possibility that Samsung (and Intel as they adapt their business model) can come back around with a little bit of luck and a lot of investment.